Why is Imp Invulnerable during robocall

If they end up buffing the Z-Mech to be as good as it was in GW2, they need to remove his invulnerability so that he can’t be used as a kamikaze when he rushes in to a group of plants and calls in the mech. It’s unfair how many times I’ve been actively shooting an imp and they can just pull out their win button and invalidate anything I do. Z-Mech should be risk reward, not pure reward.